Critical Incident Reporting in Anaesthesia: A Prospective Internal Audit

Summary Critical incident monitoring is useful in detecting new problems, identifying ‘near misses’ and analyzing factors or events leading to mishaps, which can be instructive for trainees. This study was aimed at investigating potential risk factors and analyze events leading to peri-operative critical incidents in order to develop a critical incident reporting system. We conducted a one year prospective analysis of voluntarily reported 24- hour-perioperative critical incidents, occurring in patients subjected to anaesthesia. During a one year period from December 2006 to December 2007, 14,134 anaesthetics were administered and 112(0.79%) critical incidents were reported with complete recovery in 71.42%(n=80) and mortality in 28.57% (n=32) cases. Incidents occurred maximally in 0-10 years age (23.21%), ASA 1(61.61%), in general surgery patients (43.75%), undergoing emergency surgery (52.46%) and during day time (75.89%). Incidence was more in the operating theatre (77.68%), during maintenance (32.04%) and post-operative phase (25.89%) and in patients who received general anaesthesia (75.89%). Critical incidents occurred clue to factors related to anaesthesia (42.85%), patient (37.50%) and surgery (16.96%). Among anaesthesia related critical incidents (42.85% n=48/112), respiratory events were maximum (66.66%) mainly at induction (37.5%) and emergence (43.75%), and factors responsible were human error (85.41%), pharmacological factors (10.41%) and equipment error (4.17%). Incidence of mortality was 22.6 per 10, 000 anaesthetics (32/14,314), mostly attributable to risk factors in patient (59.38%) as compared to anaesthesia (25%) and surgery (9.38%). There were 8 anaesthesia related deaths (5.6 per 10, 000 anaesthetics) where human error (75%) attributed to lack of judgment (67.50%) was an important causative factor. We conclude that critical incident reporting system may be a valuable part of quality assurance to develop policies to prevent recurrence and enhance patient safety measures.


Introduction
In recent years anaesthesia, in spite of low mortality, is still associatedwith significant morbidity. There appears to be considerable conformity that anaesthesia risk is an important public health concern and that it is reducible 1 . Further, there is reason to believe that a substantive portion of that risk is related to human error resulting from errors in management or deviation from accepted practice 2 . If the frequency of error has to be decreased, a clearer understanding of that process is needed, the circumstances that encourage error should be identified and therelative frequencies of different classes of errors should be established.
Since its early adoption in the field of aviation 3 and later in the field of anaesthesia 4,5 ; the collection of data on criticalincidents is gaining acceptance in anaesthesia. Howeverthere are stillsporadic studies 6-8 from the developing countries which have tried to analyze and evaluatethe frequency of criticalincidents "related" to anaesthetic procedures.
Ouraim wasto identifythe incidence,outcome and potential riskfactors leadingto criticalincidents during anaesthesia in a generaltertiary care teaching hospital cateringto mostlytribal patientsand to promote voluntary reportingof criticalincidents in our department.

Methods
After obtaining approvalfrom the hospital ethics committee, a one year prospective analysis of perioperative criticalincidents was conducted in a tertiary care teaching hospitalsituated in a tribalbelt from December 2006 to December 2007. Since it was an observationalstudy without any intervention, consent from patient was not required.
In a faculty meetingof the department, it was decided to implement'criticalincidentreporting' asa quality assurance measure and anaesthesiologists were asked to report 24-hour-perioperative critical incidents, occurring in patients subjected to anaesthesia.A critical eventwas defined as "An event under anaesthesia care which had the potential to lead to substantial negative outcome (ranging from increased length ofhospital stay to death or permanent disability or cancelled operative procedure) if left to progress" 4,9 . Indigenous "CriticalIncident ReportingForm" was developed and were made available in all the operation theatres, post operative wards and Intensive Care Units or High Dependency Units. Anaesthesiologists were regularly motivated and reminded to report criticalincidents on an anonymous and voluntarybasis and care was taken to maintain complete confidentiality. In these forms, detailed contextual information duringrecording of an event which would enhance the subsequent review of the incident was also included.
The criticalincident reportingform had two parts: 1. Descrip tion part: It was filled by anaesthesiologists who were conducting the case. Patient's age, sex, ASAgrading, previous systemic involvement, emergency/elective surgery, surgical specialty , factors related to anaesthesiologist conducting the case, time, type of anaesthesia, place and phase of occurrence of critical incident , time and means of detection, type and details of systemic event and substantialnegative outcome were recorded.
2. Analysis part:Allcompleted forms of criticalin-cidents includingmortalitywere reviewedand analyzed bysenior consultantanaesthesiologist ofthe department. These critical incidentswere later assigned to factors attributableto eitherpatient oranaesthesiaorsurgery.When only oneof these factors was responsible itwas defined as "totally attributable" and ifpatient factor was associated with either anaesthesiaor surgery factor itwas defined as "partially attributable" to anaesthesia and surgery respectively.Anaesthesia related critical incidents and mortality were furtheranalyzed for factors responsible like equipment error, pharmacologicalfactor and human error including lackof judgment, or skill, or experience and failure to check.
Data were expressed as number and proportion to calculate incidence.

Results
During the one year study period 14,134 anaesthetics were administered and 112(0.79%) critical incidents were reported with complete recovery in 80(71.42%) and mortality in 32(28.57%) cases.

Fig 1 Distribution of events in perioperative period
trainingfor postgraduation conduct cases under the supervisionofsenior consultants. Criticalincidents occured in 36cases (32.14%) which were being conducted independently by resident doctors with less than 3 years experience. In rest of the cases resident doctors were supervised by consultants with experience of 3-5 years (n=45, 40.17%) or more than 5 years (n=41, 27.67%).
From a total of 112 reported critical incidents, cardiac arrest occurred in 41 cases (36.6%, 29 per 10,000 anaesthetics) out of which 9 cases (8.03%) recovered completely and 32(28.57%) had a fatal outcome (22.6per 10,000 anaesthetics ). The occurrence of criticalincidents led to postponement of surgery in only 2cases: one occurred duringinduction of anaesthesia (7-year-male child posted for herniotomy under general anaesthesia had hypoxia and bradycardia during induction leading to cardiac arrest but was resuscitated with full recovery) and the other occurred duringpronepositioning ofthe patient (57yearold male posted for lumbar laminectomy had paroxysmal supraventricular tachycardia with hypotension that responded to esmolol).

Discussion
Internal audits based on recording of critical incidents in institutions are imperative for the speciality of anaesthesia, firstly, to study the changes in patient outcome whichunderline theimprovement in standards of anaesthesia care and secondly, for sharingand discussingthese critical incidents to evolve new policiesto prevent recurrences [10][11][12][13]   Many variables (patient status, surgicalprocedure, and surgicalexpertise) make the delineation of anaesthesia related factors obscure. The relative rarity of adverse outcome makes it imperative to study large number of patients over time. The methods used to collect information about safety of anaesthesia and to establish the risk factors have included peer reviews, hospital audit, reports to medical defense societies 14 , retrospective 4 and prospective studies 15 . A prospective reporting system avoids the problems of inaccurate recalland allows warnings and advice to be issued if necessary, soon after the occurrence 15 . In our institution we conducted a prospective survey of 24-hour perioperative criticalincidents over a one year period and found 112 critical incidents with over all incidence of 0.79% of which 0.33% (n=48) were attributable to anaesthesia. The frequency of incidents reported from different institutions have varied from 0.28% to 2.8% 16,17 while higher incidence of 12.1% 18 and 10.6% 19 have also been reported. The vast difference in these figureslies in the factthat interpretationof critically ill in anaesthesia varies according to individual perception of an incident and to an ambiguity in how these are applied in practice. There is reluctance to report seemingly minor events while some major events go unreported for fear of retribution, lack of motivation and  lackof acceptance of the fact that it could be beneficial as an educational tool 20 .
Recent studies define mortality associated with anaesthesia as death under, as a result of, or within 24 hour of an anaesthetic 21,22 . In literature, crude anaesthetic mortality(i.e. combined anaesthetic and surgical mortality) associated with anaesthesia ranges between 10-30 per 10,000 anaesthetics [23][24][25] . It has been suggested that anaesthesia related mortality has decreased in the last three decades and currently ranges from 0.05 to 10 per 10,000 21,26,27 and in most developed countries lies between 0.12-1.4 per 10,000anaesthetics 28 .
In our audit, crude anaesthetic mortality was 22.6 per 10,000 and anaesthesia related mortality was 5.6 per 10,000 anaesthetics. The reasons for higher mortality ratein ouraudit as compared todeveloped countries may be due to the fact that we do not have an effective primary and secondary health caresystem in our country, resulting in tertiary care hospitals like ours dealing with more poorly optimized, sicker patients.Anaesthesia related mortality figures may wellbe different in the developing countries where only limited trained work force, monitoring and training facilities are available 25,29 .
Independent predictorsof operativemortality cited in literature includeadvanced and pediatric (less than 1 year) age group as well as male gender 30,31 . We found no correlation between sex and occurrence of critical incidents or mortalities. There was no association of mortality with agehowever maximum critical incidents occurred in 0-10 year age group, which shows that the paediatric population are always at riskof anaesthesia because of anatomicaland physiological reasons 18,28,32 .
In our audit, incidence of critical incidents and mortalities was maximum inASA I and II patients, as maximum surgicalpatients belongedto thisphysicalstatus. In higherASA physicalstatus senior consultant attendance,stringent monitoringand extravigilance could be a reason for less incidence 6,7 .Though some authors have found a clearrelationship betweenincreasingASA gradeand therisk ofcriticalincidents particularly physiological incidents 18 and mortality 8,28 . Therehas been a slightly higher incidence of critical incidents 18 and mortalities 8,28,33 in emergency surgery as compared to elective surgery. Poor optimization of patient's pre-operative status, non-availability of equipments, emergency drugs, investigation facilities and poor operating conditions are allcontributory factors inemergency situation inthe developingcountries.
Criticalincidents mostly occurred during the daytime 7 coinciding withpeakworkinghours inour institution. However it could beargued that compliance with reportingis low at late hours. General surgery patients werefound morevulnerable to occurrence ofcriticalincidents which may be due to more number of patients operated under general surgery, more chance of fluid and electrolyte imbalance andsepsis in these patients 6,9 . Wefound incommon withothers thatthefrequency ofcriticalincidentsand mortalitywas higherwith general thanneuraxialanaesthesia 6,28,31,33 .However thismay be because many high risksurgeries are performed under generalanaesthesia includingcardiac, thoracicand neurosurgicalprocedures. Likewise there may be abias towards general anaesthesia in emergency settings or in patientswith co-existingmedical conditions.The most comprehensiverecent surveyof cardiac arrest incidence during neuraxialanaesthesia reported as 2.7per 10,000 anaesthetics 33 is nearly similar to our study (3.4 per10, 000).Improved knowledge of neuraxialblock physiology and the use of new local anaesthetics with fewer side effects,associated withmore routinelyused oxygen monitoring through pulseoximetry hassubstantially decreased the possibility of major complications during neuraxialanaesthesia.
We found no correlation between occurrence of critical incidents and mortalities and experience level of anaesthesiologist 7,32 . It hasbeen shownthat fatigueadversely affects the professional performance of anaesthetists 34 .Since our resident doctorshave approximately an8hourly work schedulewith an average work force of 1-2 anaesthesiologist per case , there were no reports of stress, haste,inattention, fatigueor inadequate help as reported by other workers 32,35. Operatingroom was observed as a vulnerable site for occurrence of critical incidents 7,9 . Induction and maintenance phase have been considered as "incident rich phase" 6, 8 but we found a higher incidence in the maintenance and post-operative phase, probably the latter could be attributable to the inadequate post-operative monitoringand careavailable in our institution. However anaesthesia related incidents occurred maximally during emergence and induction which are similar to other studies 6, 7, 9 . Critical incidents related to airway management have been found in 17-34% of incidents 36,37 and airway management has been shownto contribute to approximately one quarter of anaesthesia related deaths 21,22,27 . In our auditrespiratory causes were more frequently responsible for anaesthesia related criticalincidents and mortality was mainly due to laryngospasm, hypoxia, esophagealintubation, bronchospasm and aspiration.
All anaesthesiologists aspire to an anaesthesia "system" that is completely safe. However, any system operated by human beings is subject to human failure; this is both normal and inevitable 38 . Because patterns of human error in anaesthesia as elsewhere, are identifiable predictable and repetitive, they lend themselves to classification and analysis 39 . From such analysis we gain a clearer understanding of how anaesthetists behave, which is an important step in the logical evaluation of strategies to make such failures less common.
In our audit human error has been implicated as the major cause of anaesthesia relatedcritical incidents 3,4,15,32,35,40 and mortality 8,33 . Lack of judgment or experience, skilland failure to checkwere the most frequently reported factors for human errors. Thus there are elements of human error in majority of anaesthesia related criticalincidentsand mortalities,although themajority of such failureswere recognizedandinterceptedbeforethey led to an adverseoutcome. It is known that the basis for all accidentsor nearaccidents in any situation is unsafe practice or working condition 2 .
There may have been somemethodological weakness associated withour study. Firstly, under-reporting since itwas based on adverseevents beingvoluntarily reported by faculty and residents and it seems that the anaesthesiologistsreport majoradverse eventsmore accurately andfrequentlyratherthan minorevents.Secondly critical incidents reported in this study over a one year period representonly aproportion ofallmishapsthat occurinassociation withanaesthesiaresultingin avery small samplesize to calculate statisticalsignificance ofrisk factors.
To conclude, anaesthesia continues to be associatedwith mortalityand morbiditydespite improvements in drugs and equipments. Human error is the most important factor in the majority of these incidents. We emphasize that strategies and protocols should be developed for increasingand updatingknowledge base to avoid errors of judgment. There is evidence that the use of checklists, protocols and improved awareness of the relevance of critical incidents can improve safety 16 . Thus critical incident reporting should be introducedin allanaesthesia departmentsas partof quality assuranceprograms toensure improvedpatient care.